Ultrasound Catheter Having Improved Distal End

ABSTRACT

A method of making an ultrasonic catheter, disposing an ultrasound member in the main lumen of a flexible catheter body; providing an intermediate member and a tip, wherein at least a tip maximum-diameter portion is disposed in the intermediate member, wherein an intermediate-member outer diameter substantially matches a main lumen inner diameter, and wherein a tip distal cross-section has a tip distal cross-section area less than a tip proximal cross-section area of a tip proximal cross-section; and attaching the intermediate member to the catheter body and to the tip, wherein at least one of the tip and the intermediate member is configured to prevent separation of the tip of the ultrasound member from the catheter body.

CROSS-REFERENCE TO RELATED APPLICATIONS

This is a divisional of U.S. patent application Ser. No. 12/218,827,filed Jul. 18, 2008, which is a continuation-in-part of U.S. patentapplication Ser. No. 12/004,984, filed Dec. 21, 2007, which is in turn acontinuation-in-part of U.S. patent application Ser. No. 11/594,663,filed Nov. 7, 2006, now U.S. Pat. No. 8,133,236, whose entiredisclosures are incorporated herein by this reference as though setforth fully herein.

BACKGROUND OF THE INVENTION Field of the Invention

The present invention pertains to medical equipment, and moreparticularly, to a therapeutic ultrasound system for ablatingobstructions within tubular anatomical structures such as blood vessels.The ultrasound system includes a protective feature that minimizes theintroduction of debris into the patient's vasculature if the ultrasoundtransmission member were to break, fracture or become dislodged during amedical procedure. The ultrasound system also includes a distal tipconfiguration that increases energy intensity and reduces perforations.

Description of the Prior Art

A number of ultrasound systems and devices have heretofore been proposedfor use in ablating or removing obstructive material from blood vessels.Ultrasound catheters have been utilized to ablate various types ofobstructions from blood vessels of humans and animals. Successfulapplications of ultrasound energy to smaller blood vessels, such as thecoronary arteries, requires the use of relatively small diameterultrasound catheters which are sufficiently small and flexible toundergo transluminal advancement through the tortuous vasculature of theaortic arch and coronary tree. However, because of its small diameter,the ultrasound transmission member which extends through such cathetersis particularly susceptible to losses in the transmitted ultrasoundenergy, and breakage. Reducing the size of the ultrasound transmissionmember, particularly the distal tip, will increase energy intensity.However, it will also make the distal tip of the ultrasound transmissionmember more prone to perforations due to inherited stiffness of thetransmission member and a smaller tip size.

Breakage of ultrasound transmission members often occurs near theproximal end thereof, generally at the coupling between the ultrasoundcatheter coupling and the ultrasound transducer. This is believed to bebecause energy concentrations and stresses are highest at these points.Thus, any external forces applied to the ultrasound transmission memberin this region may result in stresses exceeding the elastic limit of theultrasound transmission member.

Breakage of ultrasound transmission members can also occur near thedistal end thereof, generally at the area of the smallest cross-section.To minimize breakage of the ultrasound transmission wire at the distalend, a smaller distal tip with less mass or a tip made of polymer or alower density metal may be utilized to further reduce stress at thedistal in on the transmission wire. It is important that any debrisresulting from the breakage of the ultrasound transmission member not beallowed to be introduced into a patient's vasculature during a medicalprocedure.

Thus, there still exists a need to further improve efficacy of theultrasound systems and protect against breakage of the ultrasoundtransmission member during a medical procedure.

SUMMARY OF THE DISCLOSURE

It is an object of the present invention to provide an ultrasoundcatheter system with a protective feature that prevents or minimizes theintroduction of debris into the patient's vasculature if the ultrasoundtransmission member were to break or fracture during a medicalprocedure.

In order to accomplish the objects of the present invention, there isprovided an ultrasound catheter having an elongate flexible catheterbody having a lumen extending longitudinally therethrough, and anultrasound transmission member extending longitudinally through thelumen of the catheter body. The ultrasound transmission member has aproximal end that is coupled to a separate ultrasound generating device,and a distal end that terminates at the distal end of the catheter body.The ultrasound transmission member is directly attached to the guidewiretube and/or the catheter body, and such attachment can be accomplishedusing a direct attachment or via an attachment member. A radiopaquemarker or sleeve can also be positioned on the distal end of theultrasound catheter to improve its visibility.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of an ultrasound system according to thepresent invention.

FIG. 2 is a cross-sectional view of the distal end of an ultrasoundcatheter that can be used with the system of FIG. 1 according to oneembodiment thereof.

FIG. 3 is a side sectional view of an ultrasound transmission memberthat can be used with the system of FIG. 1.

FIGS. 4-9 are cross-sectional views of the distal end of variousultrasound catheters that can be used with the system of FIG. 1according to different embodiments thereof.

FIG. 10 illustrates the distal end of an ultrasound catheter accordingto another embodiment of the present invention that can be used with thesystem of FIG. 1, where the ultrasound transmission member is attachedto the guidewire tube.

FIG. 11 is a front view of the distal end of the catheter of FIG. 10.

FIG. 12 illustrates a modification that can be made to the ultrasoundcatheter of FIG. 10 with a radiopaque marker located on the distalportion of the guidewire lumen.

FIGS. 13a and 13b illustrate a modification that can be made to theultrasound catheter of FIG. 10 with the ultrasound transmission memberattached to the guidewire tube and the catheter body.

FIGS. 14a and 14b illustrate a modification that can be made to theultrasound catheter of FIG. 10 with a radiopaque marker located on thedistal portion of the ultrasound transmission member.

FIGS. 15a and 15b illustrate a modification that can be made to theultrasound catheter of FIG. 10 with a radiopaque marker positioned onthe distal tip and a radiopaque marker positioned partially on thecatheter body and partially on the distal tip.

FIGS. 16-18 illustrate modifications that can be made to the ultrasoundcatheter in FIG. 5.

FIG. 19 illustrates modifications that can be made to the ultrasoundcatheter of FIG. 10.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The following detailed description is of the best presently contemplatedmodes of carrying out the invention. This description is not to be takenin a limiting sense, but is made merely for the purpose of illustratinggeneral principles of embodiments of the invention. The scope of theinvention is best defined by the appended claims. In certain instances,detailed descriptions of well-known devices, compositions, components,mechanisms and methods are omitted so as to not obscure the descriptionof the present invention with unnecessary detail.

FIG. 1 illustrates an ultrasound system according to the presentinvention for use in ablating and removing occlusive material inside thevessel of an animal or human. Referring to FIGS. 1 and 2, the ultrasoundsystem includes an ultrasound catheter device 10 which has an elongatecatheter body 11 having a proximal end 12, a distal end 14, and definingat least one lumen 15 extending longitudinally therethrough. Theultrasound catheter device 10 is operatively coupled at its proximal end12, by way of a Y-connector 18, a catheter knob 20, and a slide collar22, to an ultrasound transducer 24. The ultrasound transducer 24 isconnected to a signal generator 26, which can be provided with a footactuated on-off switch 28. The signal generator 26 can be supported byan IV pole 27. When the on-off switch 28 is depressed, the signalgenerator 26 sends an electrical signal to the ultrasound transducer 24,which converts the electrical signal to ultrasound energy. Suchultrasound energy subsequently passes through the catheter device 10 andis delivered to the distal end 14. A guidewire 25 may be utilized inconjunction with the catheter device 10, as will be more fully describedbelow.

The catheter body 11 is formed of a flexible polymeric material such asnylon (Pebax™) manufactured by Atochimie, Cour be Voie, Hauts Ve-Sine,France. The flexible catheter body 11 is preferably in the form of anelongate tube having one or more lumens extending longitudinallytherethrough. The catheter body 11 defines a main lumen 15. Extendinglongitudinally through the main lumen 15 is an elongate ultrasoundtransmission member 16 having a proximal end which is removablyconnectable to the ultrasound transducer 24 via a sonic connector (notshown) such that ultrasound energy will pass through the ultrasoundtransmission member 16. As such, when the foot actuated on-off switch 28operatively connected to the ultrasound transducer 24 is depressed;ultrasound energy will pass through the ultrasound transmission member16 to the distal end 14 of the catheter body 11.

A guidewire port 58 is provided in the catheter body 11 at any locationalong the catheter body 11. A guidewire lumen 60 extends from theguidewire port 58 through the main lumen 15 of the catheter body 11 in amanner that is concomitant to the length of the ultrasound transmissionmember 16. In one embodiment, the guidewire port 58 can be provided at alocation that is closer to the proximal end 12 than to the distal end 14of the catheter.

In one embodiment, the ultrasound transmission member 16 may be formedof any material capable of effectively transmitting the ultrasonicenergy from the ultrasound transducer 24 to the distal end 14 of theultrasound transmission member 16, and is preferably made from metal ormetal alloys. It is possible to form all or a portion of the ultrasoundtransmission member 16 with one or more materials which exhibitsuper-elasticity. Such materials should preferably exhibitsuper-elasticity consistently within the range of temperatures normallyencountered by the ultrasound transmission member 16 during operation ofthe catheter device 10. Specifically, all or part of the ultrasoundtransmission member 16 may be formed of one or more metal alloys knownas “shape memory alloys”. Examples of super-elastic metal alloys whichare usable to form the ultrasound transmission member 16 of the presentinvention are described in detail in U.S. Pat. Nos. 4,665,906 (Jervis);4,565,589 (Harrison); 4,505,767 (Quin); and 4,337,090 (Harrison). Thedisclosures of U.S. Pat. Nos. 4,665,906; 4,565,589; 4,505,767; and4,337,090 are expressly incorporated herein by reference insofar as theydescribe the compositions, properties, chemistries, and behavior ofspecific metal alloys which are super-elastic within the temperaturerange at which the ultrasound transmission member 16 of the presentinvention operates, any and all of which super-elastic metal alloys maybe usable to form the super-elastic ultrasound transmission member 16.

The frontal portion of the Y-connector 18 is connected to the proximalend 12 of the catheter 10 using techniques that are well-known in thecatheter art. An injection pump 54 or IV bag (not shown) or syringe (notshown) can be connected, by way of an infusion tube 55, to an infusionport or sidearm 72 of the Y-connector 18 (see FIG. 1). The injectionpump can be used to infuse coolant fluid into and/or through the mainlumen 15 of the catheter 10, with the coolant fluid exiting viairrigation outlets 32 (see FIG. 2) provided adjacent the distal end 14of the catheter 10. Such flow of coolant fluid may be utilized toprevent overheating of the ultrasound transmission member 16 extendinglongitudinally through the main lumen 15. Such flow of the coolant fluidthrough the main lumen 15 of the catheter 10 also serves to bathe theouter surface of the ultrasound transmission member 16, therebyproviding for an equilibration of temperature between the coolant fluidand the ultrasound transmission member 16. Thus, the temperature and/orflow rate of coolant fluid may be adjusted to provide adequate coolingand/or other temperature control of the ultrasound transmission member16. The irrigation fluid can include a pharmacological agent and/ormicrobubbles.

In addition to the foregoing, the injection pump 54 or syringe may beutilized to infuse a radiographic contrast medium into the catheter 10for purposes of imaging. Examples of iodinated radiographic contrastmedia which may be selectively infused into the catheter 10 via theinjection pump 54 are commercially available as Angiovist 370 fromBerlex Labs, Wayne, N.J. and Hexabrix from Malinkrodt, St. Louis, Mo.

The proximal end of the Y-connector 18 is attached to the distal end ofthe catheter knob 20 by threadably engaging the proximal end of theY-connector 18 inside a threaded distal bore (not shown) at the distalend of the catheter knob 20.

The proximal end of the ultrasound transmission member 16 is attached toa sonic connector (not shown) which is configured to effect operativeand removable attachment of the proximal end of the ultrasoundtransmission member 16 to the horn of the ultrasound transducer 24. Thesonic connector is preferably configured and constructed to permitpassage of ultrasound energy through the ultrasound transmission member16 with minimal lateral side-to-side movement of the ultrasoundtransmission member 16 while, at the same time, permitting unrestrictedlongitudinal forward/backward vibration or movement of the ultrasoundtransmission member 16. Examples of ultrasound transducers, sonicconnectors and their connections are illustrated in U.S. Pat. Nos.6,702,748, 6,855,123, 6,942,620 and 6,942,677, whose disclosures areincorporated by this reference as though set forth fully herein.

Referring to FIGS. 2 and 3, the ultrasound transmission member 16 canhave progressively tapered regions extending from the proximal end 34thereof to the distal tip 36 thereof. For example, the proximal-mostregion 38 can have a constant diameter which is the greatest diameteralong the length of the ultrasound transmission member 16. The region 38transitions at its distal end to a first tapered region 40 whichgradually decreases in diameter to its distal end to a second taperedregion 42, which gradually decreases in diameter to its distal end to athird tapered region 44, which gradually decreases in diameter to itsdistal end to the distal tip 36. Each tapered region 40, 42, 44 can havea continuous taper, and be tapered to different degrees, such that theregion 40 has a greater taper than the region 42, which in turn has agreater taper than the region 44. The distal-most part of the region 44can have the smallest diameter along the entire ultrasound transmissionmember 16. The continuously decreasing tapering from the proximal to thedistal direction shown in FIG. 3 allows for improved ultrasound energypropagation. The distal tip 36 can have a proximal section 46 whichgradually increases in diameter until it reaches the proximal end of adistal section 48. The distal section 48 can have a bulbousconfiguration having a rounded or curved distal-most end that is adaptedto contact the obstruction for ablation thereof. Thus, the distal tip 36can have an enlarged size when compared to the rest of the ultrasoundtransmission member 16 so that the distal tip 36 can function as thedistal head for the catheter 10.

In the embodiment shown in FIG. 2, the distal end 14 of the catheterbody 11 has an opening 30, and the distal tip 36 of the ultrasoundtransmission member 16 is secured to the inner wall 62 of the main lumen15 of the catheter body 11 adjacent the opening 30. The securement canbe accomplished by an attachment mechanism 64 (which can be glue,welding or fusing) at the location of the proximal section 46 and theinner wall 62, so that part of the proximal section 46 is receivedinside the main lumen 15 and with the distal section 48 of the distaltip 36 extending outside the main lumen 15 of the catheter body 11. Theopening 30 of the catheter body 11 is closed by the connection of thedistal tip 36 to the catheter body 11. The construction shown in FIG. 2directly attaches the ultrasound transmission member 16 to the catheterbody 11 (via the attachment mechanism 64), which provides additionalprotection if the ultrasound transmission member 16 experiencesbreakage. In particular, if the ultrasound transmission member 16fractures, breaks or splinters, the distal tip 36 will still remainsecured to the catheter body 11 via the attachment device 64, and willnot become dislodged from the catheter body 11. Thus, the embodiment ofFIG. 2 does not employ a separate distal head for the catheter 10, butinstead utilizes the distal tip 36 of the ultrasound transmission member16 as a distal head which is secured directly to the distal end of thecatheter body 11.

FIGS. 4-5 illustrate two different embodiments of a distal end of thecatheter 10 which utilize the same principles and general constructionas in FIG. 2, except that a distal cap is secured to the distal tip ofthe ultrasound transmission member. Therefore, the same numeraldesignations are used in FIGS. 2, 4 and 5 to designate the same orsimilar elements, except that an “a” and a “b” are added to the numeraldesignations in FIGS. 4 and 5, respectively. The differences between theembodiment of FIG. 2 and the embodiments in FIGS. 4 and 5 are describedbelow.

The distal end 14 a in FIG. 4 differs from the distal end 14 in FIG. 2in that a protective cap 66 a is secured to the distal section 48 a ofthe distal tip 36 a of the ultrasound transmission member 16 a. The cap66 a can function as the tip of the catheter 10. The distal tip 36 aitself has a different configuration from the distal tip 36 in FIG. 2 inthat the distal section 48 a is not bulbous or curved, but instead has aconstant diameter that terminates distally at a flat distal end 68 a.The cap 66 a has a cylindrical configuration with an opened proximal endand a curved or bulbous distal end 70 a. The distal section 48 a of thedistal tip 36 a is received into the hollow bore 72 a of the cap 66 avia the opened proximal end of the cap 66 a, and is secured to the cap66 a inside the bore 72 a via an attachment device 74 a (which can bethe same as the attachment device 64). The cap 66 a can be made of aradiopaque material to improve the visibility of the distal tip 36 a.

In addition, instead of the attachment mechanism 64, the embodiments ofFIGS. 4-5 provide an intermediate member 64 a. The intermediate member64 a can be a cylindrical component that is positioned around theultrasound transmission member 16 a, and between the ultrasoundtransmission member 16 a and the inner wall 62 a of the catheter body 11a. The intermediate member 64 a (as well as 64 and 64 b) is preferablymade from a material that does not effectively transfer or conduct heat,and which is easy to attach to the ultrasound transmission member 16 aand the catheter body 11 a. Examples of the material can include certainepoxies, polymers, plastics and rubber. According to one embodiment, theintermediate member 64 a can be fused to the ultrasound transmissionmember 16 a and the inner wall 62 a. According to another embodiment,the intermediate member 64 a can be bonded to the ultrasoundtransmission member 16 a and the inner wall 62 a. According to yetanother embodiment, the intermediate member 64 a can be fused to theultrasound transmission member 16 a and bonded to the inner wall 62 a.The intermediate member 64 a serves as a safety feature to hold theultrasound transmission member 64 a within the catheter body 11 in theevent the ultrasound transmission member 16 a experiences breakage at alocation proximal to the intermediate member 64 a. However, theintermediate member 64 a will not be able to hold the distal tip 36 a ifthe breakage occurs at the distal tip 36 a.

The distal end 14 b in FIG. 5 differs from the distal end 14 a in FIG. 4in the following ways. First, the guidewire port 58 a, guidewire 25 a,and guidewire lumen 60 a have been omitted. Second, the distal tip 36 bitself has a different configuration from the distal tip 36 a in FIG. 4in that a distal extension 76 b extends distally from the distal section48 b. The distal extension 76 b has a smaller constant diameter than thediameter of the enlarged distal section 48 b, and the distal extension76 b is received into the hollow bore 72 b of the cap 66 b via theopened proximal end of the cap 66 b, and is secured to the cap 66 binside the bore 72 b via an attachment mechanism 74 b (which can be thesame as the attachment mechanism 64). The cap 66 b can also be made of aradiopaque material to improve the visibility of the distal tip 36 b.

Third, the intermediate member 64 b in FIG. 5 has a differentconfiguration as the intermediate member 64 a. The intermediate member64 b has a generally conical configuration, having a wider diameter atits distal end 78 b (which resembles the base of the cone) and anarrower diameter or dimension at its proximal end 80 b (which resemblesthe narrowed tip of a cone). The hollow interior 82 b of theintermediate member 64 b has the greatest inner diameter adjacent itsdistal end 78 b and decreases to its smallest inner diameter adjacentthe proximal end 80 b. This configuration for the intermediate member 64b allows the ultrasound transmission member 16 b to be fitted andretained inside the hollow interior 82 b without the need to directlyattach the ultrasound transmission member 16 b to the intermediatemember 64 b. Specifically, the sections 46 b, 48 b can be retainedinside the hollow interior 82 b, with the transition between the region44 b and the distal tip 36 b (i.e., where the diameter of the ultrasoundtransmission member 16 b is the smallest) received in the narrow openingof the proximal end 80 b of the intermediate member 64 b. In otherwords, the proximal end 80 b overlaps a dimensional step (i.e., thetransition between the region 44 b and the distal tip 36 b) on theultrasound transmission member 16 b. The distal extension 76 b extendsthrough another opening at the distal end 78 b of the intermediatemember 64 b. To provide additional protection or safety, any or all ofthe sections 46 b, 48 b can also be bonded to the inner wall of theintermediate member 64 b. The outer surface 84 b of the intermediatemember 64 b may be attached to the opened distal end of the catheterbody 11 b by bonding, fusing or glue, and part of the intermediatemember 64 b extends beyond the distal end of the catheter body 11 b.

Comparing the embodiments of FIGS. 4 and 5, the intermediate member 64 bhas an “overlapped” configuration, which provides added protectionbecause the intermediate member 64 b is seated on a dimensional stepalong the ultrasound transmission member 16 b, and will always hold theproximal portions of the ultrasound transmission member 16 b within thecatheter body 11 b as long as the intermediate member 64 b is attachedto the catheter body 11 b.

FIG. 6 illustrates a modification that can be made to the embodiment inFIG. 4. The embodiments in FIGS. 4 and 6 utilize the same principles andgeneral construction, so the same numeral designations are used in FIGS.4 and 6 to designate the same or similar elements, except that a “c” isadded to the numeral designations in FIG. 6.

In FIG. 6, the catheter body 11 c, the guidewire port 58 c, theguidewire lumen 60 c, the guidewire 25 c, the ultrasound transmissionmember 16 c and the cap 66 c can be the same as the catheter body 11 a,the guidewire port 58 a, the guidewire lumen 60 a, the guidewire 25 a,the ultrasound transmission member 16 a and the cap 66 a in FIG. 4. Theprimary difference is that the intermediate member 64 a is now embodiedin the form of an anchor wire 64 c, which can be either a polymer or ametal. One end 86 c of the wire 64 c can be attached (e.g., by glue,fusing, bonding) to the inner wall 62 c of the catheter body 11 c, andthe other end 88 c of the wire 64 c can be attached (e.g., by glue,bonding or welding) to the distal tip 36 c and to the cap 66 c. If theultrasound transmission member 16 c breaks at any location, then theultrasound transmission member 16 c will be retained inside the catheterbody 11 c.

FIG. 7 illustrates a modification that can be made to the embodiment inFIG. 6. Specifically, the embodiments in FIGS. 6 and 7 are the sameexcept that the guidewire port 58 c, the guidewire lumen 60 c and theguidewire 25 c are omitted in FIG. 7, and the anchor wire 64 d isattached to the distal end of the ultrasound transmission member 16 dbut not attached to the cap 66 d. Therefore, the same numeraldesignations are used in FIGS. 6 and 7 to designate the same elements,except that a “d” is added to the numeral designations in FIG. 7, and nofurther description of the elements in FIG. 7 is needed.

Attaching the anchor wire 64 c or 64 d to the cap 66 c or 66 d, or notattaching the anchor wire 64 c or 64 d to the cap 66 c or 66 d, providesdifferent options. Attaching the anchor wire 64 c to the cap 66 cprevents dislodgement of the cap 66 c or the distal tip 36 c if thebreakage occurs near or at the distal tip 36 c. However, breakage atsuch locations is rare, so the embodiment in FIG. 7 (where the anchorwire 64 d is not attached to the cap 66 d) can also be employed.

FIG. 8 illustrates another modification that can be made to theembodiment in FIG. 4. Specifically, the embodiments in FIGS. 4 and 8 arethe same, except that the proximal portion of the cap 66 e has anannular edge 67 e that extends into the interior of the catheter body 11e. Therefore, the same numeral designations are used in FIGS. 4 and 8 todesignate the same elements, except that an “e” is added to the numeraldesignations in FIG. 8, and no further description of the elements inFIG. 8 is needed. The annular edge 67 e is not attached to the catheterbody 11 e, and is maintained separate from the catheter body 11 e. Onebenefit which is provided by extending a portion of the cap 66 e intothe catheter body 11 e is that this arrangement provides a smooth andfriendly transition between the distal cap 66 e and the catheter body 11e. This smooth transition facilitates navigation of the distal end 14 ethrough tortuous anatomy. Also, the non-affixed tip of the catheter body11 e can result in the improved transmission of ultrasound energy fromthe transducer to the distal end 14 e.

FIG. 9 illustrates a modification that can be made to the embodiment inFIG. 5. Specifically, the embodiments in FIGS. 5 and 9 are the sameexcept that the intermediate member 64 f is completely retained insidethe catheter body 11 f, and the proximal portion of the cap 66 f has anannular edge 67 f that extends into the interior of the catheter body 11f. Therefore, the same numeral designations are used in FIGS. 5 and 9 todesignate the same elements, except that an “f” is added to the numeraldesignations in FIG. 9, and no further description of the elements inFIG. 9 is needed.

A guidewire has been included in the embodiments of FIGS. 2, 4, 6 and 8,while the guidewire has been omitted in the embodiments of FIGS. 5, 7and 9. Embodiments showing the use or omission of a guidewire are shownfor reference only. The principles of the present invention may beapplied to catheters that include, or not include, a guidewire. The useor omission of a guidewire depends upon the choice of the clinician, andis often dictated by the access difficulty or specific clinicalsituations. For example, if the target lesion is located on a straightportion of the vessel, use of a non-guidewire embodiment will befeasible and relatively easy. On the other hand, if the target lesion islocated in a tortuous location of the vessel, then use of a guidewireembodiment will help the clinician to navigate the distal tip 36 to thelocation of the lesion.

FIGS. 10-11 illustrate a different embodiment of the present inventionwhere the ultrasound transmission member is directly connected to theguidewire tube. Since the embodiment of FIGS. 10-11 utilize the similarprinciples and constructions as the other embodiments, the same numeraldesignations are used in FIG. 10 to designate the same elements as inthe earlier embodiments, except that a “g” is added to the numeraldesignations. The ultrasound catheter has an elongate catheter body 11g, and at least one lumen 15 g extending longitudinally therethrough. Aguidewire lumen is defined by a guidewire tube 60 g which extendsthrough the lumen 15 g inside the catheter body 11 g and has a distalend that extends through a distal tip or cap 66 g. The cap 66 g has atleast one irrigation outlet hole 67 g that communicates with the lumen15 g. The ultrasound transmission member 16 g extends longitudinallythrough the lumen 15 g of the catheter body 11 g, and its distal end issecured in a proximal bore of the cap 66 g. The ultrasound transmissionmember 16 g is attached adjacent its distal end to the guidewire tube 60g. The attachment can be accomplished by the direct use of glue, weldingor fusing. Also, the attachment may be accomplished by using anattachment member 65 g, which can be glued, welded or fused to theultrasound transmission member 16 g and guidewire tube 60 g. Theattachment member 65 g can be tubular. The construction shown in FIG. 10shows the ultrasound transmission member 16 g attached to the guidewiretube 60 g via the attachment member 65 g (which can be a polymer sleeve)using any applicable glue 90 g. The cap 66 g and the ultrasoundtransmission member 16 g may be made of the same or different materialsconnected together. Both these parts may also be manufactured entirelyfrom a single piece of material without the need to separately connecteach other.

FIG. 12 shows the catheter of FIG. 10 modified to include an additionalradiopaque marker 100 attached to the distal portion of the guidewiretube 60 g. If the cap 66 g is very small or made of a polymer or a lowdensity metal, these materials exhibit a relatively low visibility underfluoroscopy. In such a case, an additional radiopaque marker may beneeded to improve visibility of the distal end 14 g of the catheter. Theradiopaque marker 100 may be placed around the guidewire tube 60 g, orattached to the guidewire tube, or to the catheter body 11 g (notshown), or to the ultrasound transmission member 16 g (not shown), orboth, using any applicable methods such as a glue or thermal fusing. Theradiopaque marker 100 may also be positioned inside the distal end ofthe catheter body 11 g (not shown) or inside the distal cap 66 g (notshown). The radiopaque marker may be provided in the form of a tubularsleeve or coil (not shown). A radiopaque rod or wire (not shown)positioned inside the hole 67 g may serve the same purpose as well. Sucha sleeve, coil, rod or wire may be made of any radiopaque materialincluding but not limited to platinum or gold.

FIG. 13a shows the catheter of FIG. 10 modified so that the distal endof the ultrasound transmission member 16 g is attached to the guidewiretube 60 g and the catheter body 11 g via attachment member 65 g usingapplicable glue 90 g for further preventing or minimizing theintroduction of debris into the patient's vasculature if the ultrasoundtransmission member 16 g were to break or fracture during a medicalprocedure.

FIG. 13b shows the catheter of FIG. 10 modified so that the ultrasoundtransmission member 16 g is directly attached to the guidewire tube 60 gand the catheter body 11 g using any applicable glue 90 g, andeliminating the attachment member 65 g as shown in the FIG. 13 a.

FIG. 14a shows the catheter of FIG. 10 modified to include an additionalradiopaque marker 101 positioned on the distal portion of the ultrasoundtransmission member 16 g. Alternatively, the radiopaque marker 101 maybe positioned freely on the ultrasound transmission member 16 g andattached to the catheter body 11 g using any applicable glue 120 asshown in FIG. 14b . The radiopaque marker 101 may be positioned freelyor attached/affixed to the ultrasound transmission member 16 g using anyknown technique, including but not limited to welding, soldering,fusing, glue or bonding.

FIG. 15a shows the catheter of FIG. 10 modified to include an additionalradiopaque marker 1021 positioned solely on the cap 66 g of the catheter14 g. Alternatively, a radiopaque marker 103 may be positioned partiallyon the cap 66 g and partially on the catheter body 11 g, as shown inFIG. 15b . The radiopaque marker 1021 may be positioned freely orattached to the cap 66 g using known technique, such as welding,soldering, fusing, glue, or bonding. If the radiopaque marker 103 ispartially located on the catheter body 11 g and partially on the cap 66g, it can also be positioned freely or attached to one or both of thesecomponents.

FIG. 16 shows the catheter of FIG. 5 with the distal cap 66 h modifiedto have a radial dimensional step. The same numeral designations areused in FIG. 16 to designate the same elements as in FIG. 5, except thatan “h” is added to the numeral designations in FIG. 16. The distal cap66 h has two radial sections, a distal portion 110 which has a smallerdimension, and a proximal portion 112 which has a larger diameter thanthe portion 110. There is a transition portion 111 of the cap 66 hlocated between the distal portion 110 and the proximal portion 112. Inaddition, to improve radiopacity of the cap 66 h, a radiopaque marker104 can be located around the cap 66 h. The marker 104 can be located onthe proximal portion 112 or on the distal portion 110 (not shown). Thetransition portion 111 should be smooth without any steps or edges.

FIG. 17 shows the catheter of FIG. 16 modified to provide the distal cap66 i with two radial dimensional steps. Again, the same numeraldesignations are used in FIG. 17 to designate the same elements as inFIG. 16, except that an “i” is added to the numeral designations in FIG.17. The cap 66 i has three dimensional sections or steps, a distalportion 120 which has the smallest dimension, an intermediate portion122 which has a larger diameter than the distal portion 120, and aproximal portion 124 which has diameter that is larger than the distalportion 120 and the intermediate portion 122. A first transition portion121 is located between the distal portion 120 and the intermediateportion 122, and a second transition section 123 is located between theintermediate portion 122 and the proximal portion 124. Both transitionportions 121 and 123 may be configured in several different shapes orconfigurations, including but not limited to a rounded configuration, aflat configuration, a tapered configuration, a reverse taperconfiguration, or combinations thereof. Such a three-steppedconfiguration would further increase energy intensity (i.e., smallerarea at the energy level) and improve device efficacy.

FIG. 18 illustrates a catheter that extends the principles of FIGS. 16and 17, so the same numeral designations are used in FIG. 18 todesignate the same elements as in FIGS. 16 and 17, except that a “j” isadded to the numeral designations in FIG. 18. Unlike the embodiments inFIGS. 16 and 17, the distal cap 66 j and the ultrasound transmissionmember 16 j are made of the same piece of material, so there is noseparate attachment between them. This can be accomplished by machininglaser cut, deposition or other forming methods. The distal cap 66 j hastwo different radial dimensions, a distal portion 130 and a proximalportion 132 that has a greater diameter than the distal portion 130. Thedistal portion 130 has a longitudinally tapered configuration, while theproximal portion 132 has a continuous longitudinal configuration. Aconcave transition 133 is provided between the distal portion 130 andthe proximal portion 132. Such a transition 133 may further increase theultrasound catheter efficacy because of the additional mechanicalcutting edge 131 provided by this configuration.

FIG. 19 illustrates modifications made to the catheter in FIG. 10 wherethe distal cap 66 k is provided with a radial dimensional step having adifferent configuration to that in FIG. 10. Therefore, the same numeraldesignations are used in FIG. 19 to designate the same elements as inFIG. 10, except that a “k” is added to the numeral designations in FIG.19. The distal cap 66 k has two different radial dimensional sections,with a distal portion 140 and a proximal portion 142 separated by atransition portion 141. By reducing the size of the distal cap 66 kadjacent its distal-most portions (where the catheter would contact atarget tissue), the intensity of the ultrasound energy will beincreased, thereby improving the ablation capabilities of the ultrasoundcatheter 10 k. The catheter 10 k is capable of operating with aconventional guidewire 25 k. The guidewire 25 k can be positioned withinthe guidewire lumen 60 k positioned within the catheter body 11 k, andattached to the distal cap 66 k via any suitable medical grade glue 150.The catheter 10 k can be used to ablate any unwanted material in a bloodvessel or conduit in the human body. As an example, in FIG. 19, thedistal end 14 k of the catheter 10 k is positioned against anobstruction 200 (e.g., vascular abstraction or atherosclerotic plaque)located in a vessel 201. The distal portion 140 of the cap 66 k, whilepositioned against the obstruction 200 and activated, will create asmall pilot entry lumen 203 that further enhances the ablation processbecause of the higher energy intensity. Once this pilot lumen 203 hasbeen created, the ablation process caused by the larger proximal portion142 of the cap 66 k will continue. The length of the distal-most crosssectional area with the smallest diameter depends on the overall size ofthe catheter 10 k. For endovascular applications, the diameter of thecap 66 k varies between 0.2 mm to 6 mm, the length of the distal portion140 is preferably between 0.1 mm and 5 mm, and preferably about 0.5 mm.A cap 140 with such a short distal portion 140 will be less prone tounwanted perforation because of the protective effect afforded by thelarger-diameter portion 142 of the cap 66 k being located nearby.Without the smaller distal portion 140, the distal end 14 k of thecatheter 10 k would otherwise be much larger and the energy intensitywould be lower, thereby making it difficult to initiate the ablationprocess, or causing the start of the ablation process to take more time.

While the description above refers to particular embodiments of thepresent invention, it will be understood that many modifications may bemade without departing from the spirit thereof. The accompanying claimsare intended to cover such modifications as would fall within the truescope and spirit of the present invention.

1-20. (canceled)
 21. A method of making an ultrasonic catheter,comprising: providing a flexible catheter body having a main lumen;disposing an ultrasound member in the main lumen, the ultrasound memberhaving a proximal end that is configured to connect to a generatingdevice; providing an intermediate member and a tip, wherein at least atip maximum-diameter portion is disposed in the intermediate member,wherein a tip distal cross-section defines a first region and a tipproximal cross-section defines a second region and a transition isdisposed between the first region and the second region, and having anadditional region with a shape selected from one or more of flat, round,tapered, and concave, wherein an intermediate-member outer diametersubstantially matches a main lumen inner diameter, and wherein the tipdistal cross-section has a tip distal cross-section area less than a tipproximal cross-section area of the tip proximal cross-section; andattaching the intermediate member to the catheter body and to the tip,wherein at least one of the tip and the intermediate member isconfigured to prevent separation of the tip of the ultrasound memberfrom the catheter body.
 22. The method of claim 21, comprising disposinga cap on the tip.
 23. The method of claim 22, comprising disposing theultrasound member in the tip.
 24. The method claim 23, comprisingproviding the intermediate member with an intermediate member proximalcross-section having an intermediate member proximal cross-section areaand an intermediate member distal cross-section having an intermediatemember distal cross-section area, wherein the intermediate memberproximal cross-section area is less than the intermediate member distalcross-section area.
 25. The method claim 21, comprising providing theintermediate member with an intermediate member proximal cross-sectionhaving an intermediate member proximal cross-section area and anintermediate member distal cross-section having an intermediate memberdistal cross-section area, wherein the intermediate member proximalcross-section area is less than the intermediate member distalcross-section area.
 26. The method of claim 25, comprising disposing acap on the tip.
 27. The method of claim 25, comprising disposing adistal end of the ultrasound member in the tip.
 28. The method of claim21, wherein the ultrasound member comprises the tip.
 29. The method ofclaim 28, comprising disposing a cap on the tip.
 30. A method of makingan ultrasonic catheter, comprising: providing a flexible catheter bodyhaving a main lumen and a guide wire lumen; disposing an ultrasoundmember in the main lumen, the ultrasound member having a proximal endthat is configured to connect to a generating device; providing a tiphaving a tip distal cross-section that defines a first region and a tipproximal cross-section that defines a second region and having atransition disposed between the first region and the second region, andhaving an additional region with a shape selected from one or more offlat, round, tapered, and concave, wherein the tip distal cross-sectionhas a tip distal cross-section area less than a tip proximalcross-section area of the tip proximal cross-section; and attaching anintermediate member to each of the catheter body and the tip, wherein atleast a tip maximum-diameter portion is disposed in the intermediatemember, and wherein the tip is configured to prevent separation of theintermediate member from the catheter body.
 31. The method of claim 30,comprising disposing a cap on the tip.
 32. The method of claim 31,comprising disposing a distal end of the ultrasound member in the tip.33. The method of claim 30, comprising disposing a distal end of theultrasound member in the tip.
 34. The method of claim 30, wherein theultrasound member comprises the tip.
 35. The method of claim 34,comprising disposing a cap on the tip.
 36. A method of making anultrasonic catheter, comprising: providing a flexible catheter bodyhaving a main lumen and a guide wire lumen; disposing an ultrasoundmember disposed in the main lumen, the ultrasound member having a distaltip, wherein the distal tip has a tip distal cross-section that definesa first region, a tip proximal cross-section that defines a secondregion, and a transition disposed between the first region and thesecond region, and having an additional region with a shape selectedfrom one or more of flat, round, tapered, and concave; and attaching anintermediate member to each of the flexible catheter body and the distaltip, the intermediate member having a proximal cross-section with anarea less than a distal cross-section, and the intermediate memberhaving an outer diameter that substantially matches a main lumen innerdiameter.
 37. The method of claim 36, comprising disposing a cap on thedistal tip.
 38. The method of claim 36, wherein the ultrasound member isdisposed in the tip, at least a tip maximum-diameter portion is disposedin the intermediate member, a tip distal cross-section has an area lessthan a tip proximal cross-section, and the tip is configured to preventseparation from the flexible catheter body.
 39. The method of claim 38,comprising disposing a cap on the distal tip.
 40. The method of claim36, wherein the intermediate member is configured to prevent separationof the tip from the flexible catheter body.